Liquid crystal display device

ABSTRACT

The present invention provides a liquid crystal display device which can obviate cutting off of a peripheral region of the liquid crystal display device which is provided with an inspection circuit and can surely perform the inspection of an image display even when the peripheral region is narrowed. On a substrate of the liquid crystal display device, a pixel region which is comprised of a plurality of gate lines and a plurality of drain lines and a peripheral region which surrounds the pixel region are formed. A turn-on inspection terminal of the liquid crystal display device are formed on the peripheral region and a semiconductor chip for driving liquid crystal is formed on the inspection terminal. The semiconductor chip is electrically insulated from the inspection terminal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of nonprovisional U.S. applicationSer. No. 11/082,032 filed on Mar. 17, 2005, now U.S. Pat. No. 7,251,009which is a Continuation of nonprovisional application Ser. No.10/621,457 filed on Jul. 18, 2003 now U.S. Pat. No. 6,882,397. Priorityis claimed based on U.S. application Ser. No. 11/082,032 filed on Mar.17, 2005, which claims the priority of U.S. application Ser. No.10/621,457 filed on Jul. 18, 2003, which claims the priority of JapaneseApplication 2002-263571 filed on Sep. 10, 2002.

BACKGROUND OF THE INVENTION

The present invention relates to a liquid crystal display device, andmore particularly to a liquid crystal display device which narrows aperipheral region surrounding an image display region.

As an image display device, a liquid crystal display device has beenknown. Particularly, a liquid crystal display device which uses thinfilm transistors can display images of high definition and hence, such aliquid crystal display device is used as an image display device of atelevision set, a display for a personal computer or an image displaydevice of a portable terminal.

Recently, with respect to the image display device, while an outer frameis miniaturized, an image display region is enlarged to improve therecognition performance of information. Further, due to the demand forhigher definition of display images, the number of pixels is increasedand, at the same time, the numbers of gate lines and the drain lines arealso increased.

FIG. 5 is a wiring diagram of a transparent substrate and a peripherythereof of a conventional liquid crystal display device.

The liquid crystal display device is configured by arranging two sheetsof transparent substrates such that they face each other in an opposedmanner while inserting a liquid crystal layer therebetween. On aliquid-crystal-side surface of the first transparent substrate PNL1, aplurality of gate lines GW which extend in the X direction (lateraldirection) and are arranged in parallel in the Y direction (longitudinaldirection) and a plurality of drain lines (or source lines) DW which areinsulated from the gate lines GW, extend in the Y direction and arearranged in parallel in the X direction are provided. Counter electrodesand color filters are formed on the second transparent substrate.

In a region surrounded by two neighboring gate lines GW and twoneighboring drain lines DW, a switching element which is turned on inresponse to a scanning signal from the gate line and a pixel electrodeto which a video signal is supplied from the drain line through theswitching element are formed thus constituting a pixel. A region inwhich a plurality of these pixels are formed constitutes a pixel regionAR.

A peripheral region PA is provided around the pixel region AR. In theperipheral region PA, a drain drive circuit, a gate drive circuit, andlines which connect these drive circuits to gate lines and the drainlines in the pixel region are formed.

The liquid crystal display device for a portable terminal has a narrowperipheral region. Circuit chips for driving liquid crystal (hereinafterreferred to as “drivers”) and lines for connection are arranged in theperipheral region of the liquid crystal display device.

Further, the second transparent substrate is formed smaller than thefirst transparent substrate. With respect to the first transparentsubstrate, in a region which does not face the second transparentsubstrate in an opposed manner, a drain driver DDr and a gate driver GDrare formed.

However, the liquid crystal display device which has enlarged the imagedisplay region has the narrow peripheral region and hence, it isimpossible to ensure a space for mounting inspection terminals forinspecting by turning on a liquid crystal display element. Further,after inspection, the inspection terminals are cut off. Accordingly, themass productivity of the conventional liquid crystal display device islow.

Even when the inspection terminals are not mounted, it is possible touse connection terminals with the gate driver for gate lines orconnection terminals with the drain driver for drain lines as inspectionterminals. However, in such a case, the alignment of terminals of aninspection device and the connection terminal becomes difficult.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, the liquid crystaldisplay device includes transparent substrates which are arranged toface each other in an opposed manner by way of liquid crystal. Onetransparent substrate includes a plurality of gate lines which extend inthe X direction (lateral direction) and are arranged in parallel in theY direction (longitudinal direction) and a plurality of drain (orsource) lines which are insulated from the plurality of gate lines,extend in the Y direction and are arranged in parallel in the Xdirection. Further, this transparent substrate includes a peripheralregion which surrounds a pixel region formed by the plurality of gatelines and the plurality of drain lines.

The first substrate includes the pixel region in which pixel electrodesare formed and the peripheral region which surrounds the pixel region,and a turn-on inspection terminal of the liquid crystal display deviceare formed on the peripheral region. Over the inspection terminal, asemiconductor chip for driving the liquid crystal is arranged such thatthe semiconductor chip is electrically insulated from the inspectionterminal.

The semiconductor chip is comprised of two semiconductor chipsconsisting of a drain driver and a gate driver, and the drain driver isarranged over the inspection terminal.

The inspection terminal includes a drain-line inspection terminal and agate-line inspection terminal.

According to a second aspect of the present invention, the liquidcrystal display device is a liquid crystal display device which includesa liquid crystal layer between a first substrate and a second substrate,wherein the first substrate includes a pixel region having pixelelectrodes and a peripheral region which surrounds the pixel region,three drain-line inspection terminals and four gate-line inspectionterminals are arranged in the peripheral region, and a semiconductorchip is arranged over the three drain-line inspection terminals and thefour gate-line inspection terminals.

Further, the drain-line inspection terminals consist of a drain-lineinspection terminal for red, a drain-line inspection terminal for greenand a drain-line inspection terminal for blue.

Neighboring gate lines are connected to different gate-line inspectionterminals.

The present invention can provide a liquid crystal display device whichcan obviate cutting off of the peripheral region of the liquid crystaldisplay device on which an inspecting circuit is formed and can surelyperform the inspection of image display even when the peripheral regionis narrowed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a substrate of a liquid crystal display deviceaccording to the present invention.

FIG. 2A to FIG. 2D are views showing inspection waveforms of the liquidcrystal display device according to the present invention.

FIG. 3 is a plan view of the substrate having another constitution ofthe liquid crystal display device of the present invention.

FIG. 4 is a plan view of the substrate having another constitution ofthe liquid crystal display device of the present invention.

FIG. 5 is a plan view of a substrate of a conventional liquid crystaldisplay device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention are explained inconjunction with drawings.

In respective embodiments, parts having identical functions areindicated by same reference symbols.

FIG. 1 is a plan view of a liquid crystal display device 1 according tothe present invention showing lines formed on a first substrate.Further, FIG. 1 is a plan view of the liquid crystal display device fora portable terminal in which a size of an effective screen in thediagonal direction is set to approximately 5.08 cm and also is a planview of a transparent substrate on which pixel electrodes are formed.The liquid crystal display device shown in FIG. 1 adopts an activematrix system.

The active matrix type liquid crystal display device includesrectangular substrates which are arranged to face each other in anopposed manner and a liquid crystal layer is formed between the firstsubstrate PNL1 and the second substrate PNL2. The second substrate PNL2is formed smaller than the first substrate PNL1.

On a liquid-crystal-side surface of the first substrate PNL1, gate linesGW which extend in the X direction (lateral direction) and are arrangedin parallel in the Y direction (longitudinal direction) and drain lines(or source lines) DW which are insulated from the gate lines GW, extendin the Y direction and are arranged in parallel in the X direction areformed. Holding capacitance lines SW are arranged parallel to the gatelines GW. In FIG. 1, some of the plurality of gate lines GW and theplurality of drain lines DW are described.

In each region surrounded by the gate lines and the drain lines whichcross each other, a switching element which is turned on in response toa scanning signal from the gate line and a pixel electrode to which avideo signal is supplied from the drain line DW through the switchingelement are formed thus constituting a pixel. A thin film transistor TFTis used as the switching element.

With respect to the first substrate PNL1, on a region which does notface the second transparent substrate PNL2 in an opposed manner, a draindriver DDr and a gate driver GDr are arranged. Further, the gate driverGDr and the drain driver DDr are mounted on one of short sides of thefirst substrate PNL1 in a flip-chip method. The gate driver GDr isconnected to the gate lines GW and the drain driver DDr is connected tothe drain lines DW.

A common electrode is formed on the second substrate PNL2. Further, acapacitor LC is formed by the common electrode and the pixel electrodeso as to hold a voltage.

A common line Vcom which is connected to the common electrode isarranged on the first substrate.

Lines shown in FIG. 1 are lines which are formed on the first substratePNL1.

On a peripheral region PA, gate-line inspection transistors TG anddrain-line inspection transistors TD are formed.

The gate-inspection transistors TG are formed on a long side of thefirst substrate PNL1 and are connected to one ends of the gate lines.Further, another ends of the gate lines are connected to the gate driverGDr.

The odd-numbered gate-line inspection transistors TG have one endsthereof connected to the odd-numbered gate lines GW and another endsthereof connected to the odd-numbered gate-line inspection terminal CGO.

The even-numbered gate-line inspection transistors TG have one endsthereof connected to the even-numbered gate lines GW and another endsthereof connected to the even-numbered gate-line inspection terminalCGE.

The drain-line inspection transistors TD have one ends thereof connectedto the drain lines DW and another ends thereof connected to thedrain-line inspection terminal for red CR, the drain-line inspectionterminal for green CG and the drain-line inspection terminal for blueCB.

Gates of the gate-line inspection transistors TG and the drain-lineinspection transistors TD are connected to a common inspecting switch S.

The drain driver DDr is arranged over the odd-numbered gate-lineinspection terminal CGO, the even-numbered gate-line inspection terminalCGE, the drain-line inspection terminal for red CR, the drain-lineinspection terminal for green CG and the drain-line inspection terminalfor blue CB, and an inspecting common terminal CV by way of ananisotropic conductive film. Here, the drain driver DDr and theinspection terminals are electrically insulated from each other.

An inspecting switch S is arranged below the gate driver GDr. The gatedriver GDr is also fixed to the first substrate PNL1 by way of ananisotropic conductive film. Here, the gate driver GDr and theinspecting switch terminal are electrically insulated from each other.

Due to such a constitution, it is possible to manufacture the liquidcrystal display device without enlarging the peripheral region PA.Further, since the anisotropic conductive film is adhered to theinspection terminal portions, it is possible to prevent the inspectionterminal portions from being exposed to outside air as much as possibleand hence, the electrolytic corrosion or the corrosion of the inspectionterminal portions can be suppressed.

Further, it is unnecessary to cut off portions of the substrate wherethe inspection terminal is formed and hence, the manufacturing steps ofthe liquid crystal display device can be simplified. Still further,since the step for cutting off the inspection terminal can be omitted,it is possible to suppress the generation of cut-off chips of thesubstrate and hence, the defective display attributed to dust can beobviated.

Further, by setting the inspecting switch S at a low level at the timeof driving the liquid crystal, it is possible to turn off the gates ofall inspection transistors. The substrate is provided with a terminal TVfor supplying a voltage for turning off the gates of the inspectiontransistors.

The inspection method is explained hereinafter.

FIG. 2A to FIG. 2D show driving waveforms at the time of displaying red,that is, voltage waveforms inputted to the respective inspectionterminals. FIG. 2A shows the waveform inputted to the odd-numbered gateline inspection terminal CGO, FIG. 2B shows the waveform inputted to theeven-numbered gate line inspection terminal CGE, FIG. 2C shows thewaveform inputted to the drain-line inspection terminal for red CR, andFIG. 2D shows the waveforms inputted to the drain-line inspectionterminals for green and blue CG, CB. In this embodiment, the liquidcrystal display device in a normally white is used.

To the odd-numbered gate-line inspection terminal CGO, pulse voltageshaving a period of Mms and a pulse width of Nμs are supplied. On theother hand, to the even-numbered gate-line inspection terminal CGE,pulse voltages which have a period thereof displaced from the period ofthe pulse voltages applied to the odd-numbered gate-line inspectionterminal CGO are applied. Due to such a constitution, it is possible todetect short-circuiting between the gate lines.

To the drain-line inspection terminal for red CR, a voltage whichreverses a polarity thereof every Mms is supplied. To the drain-lineinspection terminals for green and blue CG, CB, a voltage which reversesa polarity thereof every Mms is supplied.

By lowering the voltage supplied to the drain-line inspection terminalfor red CR and elevating the voltage supplied to the drain-lineinspection terminals for green and blue CG, CB, it is possible todisplay red. Here, it is possible to inspect short-circuiting betweenthe drain line for red and the drain line arranged close to the drainline for red.

In the same manner, by displaying either one of green or blue, it ispossible to inspect short-circuiting between the neighboring drainlines.

The gates of the gate-line inspection transistor TG and the drain-lineinspection transistor TD are turned on. Upon completion of theinspection, the gates of the gate-line inspection transistors TG and thedrain-line inspection transistors TD are turned off by operating theinspecting switch S. For example, by setting the inspecting switch S tothe low level at the time of driving the liquid crystal, it is possibleto turn off the gates of all inspection transistors. Since the gates ofthe inspection transistors are always turned off at the time of drivingthe liquid crystal, it is possible to display images in a stable manner.

In the liquid crystal display device shown in FIG. 1, since only oneinspecting switch S is provided, it is sufficient to provide only onevoltage supply terminal at the time of driving.

Further, upon completion of the inspection, the terminals of the draindriver DDr are connected to one ends of respective drain lines.

FIG. 3 shows a liquid crystal display device which is comprised of afirst liquid crystal display device provided with the gate driver GDrand the drain driver DDr and a second liquid crystal display device 2which is connected with the first liquid crystal display device by meansof a flexible printed circuit board FPC. Some drain lines DW are used bythe first liquid crystal display device and the second liquid crystaldisplay device in common.

A second common line Vcom2 which is used in the second liquid crystaldisplay device is arranged on the first substrate.

In the liquid crystal display device shown in FIG. 3, a semiconductorchip for driving liquid crystal is mounted on a short side of onesubstrate and, at the same time, terminals PD for connecting the firstliquid crystal display device to the second liquid crystal displaydevice by way of the flexible printed circuit board FPC are formed on ashort side of another substrate. Accordingly, a peripheral region isfurther narrowed. By applying the present invention to such a liquidcrystal display device, it is possible to reduce a contour of the liquidcrystal display device.

FIG. 4 shows a liquid crystal display device which houses a gate driverand a drain driver in one driver Dr. Parts having identical functions asthe parts shown in FIG. 1 are indicated by same symbols.

The drain lines DW are constituted of 398 drain lines in total rangingfrom D0 to D397. The gate lines GW are constituted of 178 gate lines intotal ranging from G0 to G177.

In the liquid crystal display device shown in FIG. 4, the gate lineswhich drive one half of a pixel region remote from the driver Dr runover a right-side peripheral region and are connected to the driver Dr,while the gate lines which drive another half of a pixel region close tothe driver Dr run over a left-side peripheral region and are connectedto the driver Dr. The drain lines are connected to the driver Dr in aregion including a center portion of a long side of the driver.

The gate lines which are connected to the driver Dr after running overthe right-side peripheral region of the substrate are connected togate-line inspection transistors TGL formed on the left side of thesubstrate.

The gate lines which are connected to the driver Dr after running overthe left-side peripheral region of the substrate are connected togate-line inspection transistors TGR formed on the right side of thesubstrate.

At a center portion of the substrate, a drain-line inspecting switchterminal S1, a drain-line inspection terminal for red CR, a drain-lineinspection terminal for green CG and a drain-line inspection terminalfor blue CB are arranged. The drain-line inspecting switch terminal S1is connected to gates of the drain-line inspection transistors TD.

At the left side of the drain-line inspection terminals, gate-lineinspection terminals which run over the right-side peripheral portion ofthe substrate and are connected to the driver Dr are arranged. As thesegate-line inspection terminals, the odd-numbered gate-line inspectionterminal CGO1, the even-numbered gate-line inspection terminal CGE1 andthe gate-line inspecting switch terminal S2 are arranged.

At the right side of the drain-line inspection terminals, gate-lineinspection terminals which run over the left-side peripheral region ofthe substrate and are connected to the driver Dr are arranged. As thesegate-line inspection terminals, the odd-numbered gate-line inspectionterminal CGO2, the even-numbered gate-line inspection terminal CGE2 andthe gate-line inspecting switch terminal S3 are arranged.

The driver Dr is fixed over these inspection terminals by way of ananisotropic conductive film. Here, the driver Dr and the inspectionterminals are electrically insulated from each other.

Due to such a constitution, it is possible to reduce the panelperipheral region which surrounds the display region.

Further, while reducing the panel peripheral region, it is also possibleto surely detect an electric short-circuiting between the gate lines GWand an electric short-circuiting between the drain lines DW.

The alignment between the inspection terminals of the display device andterminals of the inspection device can be made easily so that thedisplay device can be manufactured easily.

Since the semiconductor chip is mounted on the inspection terminals byway of the anisotropic conductive film, it is possible to prevent theinspection terminals from exposed to atmosphere whereby the breaking dueto static electricity, the electrolytic corrosion or the corrosion canbe suppressed.

1. An image display device comprising: a substrate having a plurality ofscanning signal lines and a plurality of video signal lines; and adriver chip mounted on the substrate, wherein the substrate includesvideo signal line inspection terminals and video signal line inspectiontransistors, each of the video signal line inspection transistors isarranged between one of the video signal lines and one of the videosignal line inspection terminals, the video signal line inspectiontransistors control a connection between the video signal lines and thevideo signal line inspection terminals by being turned on during aninspection and being turned off during normally image displaying, andthe driver chip is arranged over the video signal line inspectiontransistors and the video signal line inspection terminals.
 2. An imagedisplay device according to claim 1, wherein the substrate includesscanning signal line inspection terminals.
 3. An image display deviceaccording to claim 2, wherein the scanning signal line inspectionterminals includes a first scanning signal line inspection terminal anda second scanning signal line inspection terminal, and one ofneighboring two scanning signal lines is connected to the first scanningsignal line inspection terminal and another of the neighboring twoscanning signal lines is connected to the second scanning signal lineinspection terminal.
 4. An image display device according to claim 1,wherein the video signal line inspection terminals include a videosignal line inspection terminal for red, a video signal line inspectionterminal for green and a video signal line inspection terminal for blue.5. An image display device according to claim 1, wherein the imagedisplay device includes a second substrate which is arranged to face thesubstrate in an opposed manner and a liquid crystal layer disposedbetween the substrate and the second substrate.